Turbine nozzle blade and mounting therefor



June y10, 1924,

1,497,081 H. H. WAIT TURBINE NOZZLE BLADE AND MOUNTING THEREFOR Filed March zo. 192:5

par-4M V l a 22 zg f @zwi 1 Patented June 10, 1924.

HENRY II. WAIT, OF ANDERSON, INDIANA, `ASSIGrNOR TO MIDWEST ENGINE CORPORA- TION, OF INDIANAPOLIS, INDIANA, A CORPORATION 'OF DELAWARE.

TURBINE NOZZLE BLADE AND MOUNTING THEREFOR.

Application led March 20, 1923. Serial No. 626,402.

To all 'whom t may concern.' v

Be it known that I, HENRY II. WAIT, a citizen of the United States, residing at Anderson, in the countyof Madison and State of Indiana, have invented a new and useful Turbine Nozzle Blade and Mounting Therefor, of which the following is a specication.

It is the object of my invention to produce a steam-turbine nozzle formed by blades which co-operate to form the nozzle passages and which have on the blades themselves all the accurate forming for accelerating the steam, .and expanding it ifv desired; so that the parts between which the blades are mounted may be simple in form, without the necessity for complex surfaces, and may be parallel to the turbine axis; and to make such blades so that there is a minimum of joints in the higher pressure part of the steam passage., so that leakage will be minimized.

The accompanying drawing illustrates my invention: Fig. 1 is a fragmentary side elevation of the upper part of a steam-turbine diaphragm equipped with blades embodying my invention, viewed fromA thedischarge face; Fig. 2 is a development viewsubstantially on the curved line 2-2 of Fig. 1; Fig. 3 is a fragmentary section on the lines`3-3 of Figs. 1 and 2, showing the mounting of blades embodying my invention in a diaphragm, but omitting the remainder of the turbine; and Fig. 4 is a perspective view showing two blades mounted on the outer edge of a diaphragm in accordance with my invention, but with the outer clamping ring removed.

I have illustrated my invention asapplied to the blades of a diaphragm in a steam turbine, where they find a vmostv advantageous use, but this is merelyby way of example, as myblades can also be used otherwise than in a diaphragm.

As thus used in a diaphragm, the diaphragm 10 is shown as being suitably mounted within the usual casing orvhousing 1 1, to separate a space 12 in which steam is relatively quiescent from a space 13 in which is located a turbine wheel 14 having suitable moving blades 15, usually of the impulse type. The blades embodying my invention provide steam passages for receiving steam from the space 12 and discharging it at greatlyincreased speed against the moving blades 15.

The diaphragm l10 is provided withy an outer clamping ring 20, between which and the diaphragm proper there is a space in which the blades 21 embodying my invention are located. The adjacent faces 22 and 23 of the 'diaphragm 10 and `clamping ring 20 are parallel to each other, and parallel to the axis of the turbine, so that they are ordinary cylindrical surfaces in this embodiment of my invention. In any case, they are simple surfaces which can be machined easily; and if the series of blades 21 extends some distance circumferentially, it is simpler to make these faces cylindrical faces than to make them a series of plane faces; though my invention is not limited to the mounting ofthe blades between cylindrical surfaces, and does not exclude mounting them between plane faces. The blades may be held between the diaphragm 10 and clamping ring 2O in any suitable manner, but I prefer to holdthem in place and to clamp the clamping ring 2O to the diaphragm'l() by radial members 24, such as pins,y which pass inward through the clamping ring 20, completely through the hubs or larger ends of the blades 21, and into the outer edge-faceof the diaphragm 10; with additional pins 25, if desired, such as dowel pins, for preventing the blades fromturning on the members 24, the additional pins 25 being located eccentrically with respect to the pins 24 and extending between the respective blades and one of their radially abutting members.

Each blade 21 has inner and outer surfaces which fit against the surfaces 22 and 23 respectively; and like such latter surfaces are simple surfaces. These blade-surfaces are cylindrical when the surfaces 22 and 23 are cylindrical, as when the blades are mounted in a diaphragm. These two blade-surfaces are spaced apart bythe same distances that the surfaces 22 and 23 are spaced apart; so that radially considered, the blades fill the spaces between the surfaces 22 and 23. Each blade has its lattaching hub 30 which receives the pin 24; and a projecting tapering finger 31 which projects obliquely with respect to the series of blades and at its tip overlaps and abuts against the base of the finger 31 of the adjacent blade, as is clear from Fig. 4.

titl

Each tapering linger 3l has a discharge face 32 which is parallel to the series of blades and perpendicular to the axis of the turbine, the faces 32 of the series of overlapping blades all being in substantially the l back or receiving face of the tip of the over- ,lapping finger. yThis back or receiving face y34 ofeach linger flaresfrom the face 82, -and, becomes tangent with the surface of the hub by a smooth curve. This back face 34 and the surface of the hub 30 is made up of straight-line elements, extending from the inner surface to the outer surface of the blade. The face 32 is provided with a slot 35 which extends from a point quite close to the very tip of the finger back to the hub 30, which slot recedes from the plane of the face 32 substantially throughout the whole length as it goes from the tip to the hub; and in the preferred construction the botgtom face 36 of this slot is a plane surface,

and joins the surface of the hub 30 tangentially. By reason of the slot 35, the finger 3l on its discharge face has two projecting flanges 37 and 38, which extend substantially throughout the length of the faces 32 and 33. The adjacent faces 39 and 40 of the flanges 8T and 38 are parallel to each other, so that the cross-section of the slot 35 is rectangular. These faces 39 and 40 are preferably curved with the axis of the turbine as their axis, for blades on the smaller-size turbines: though, especiall)v for the larger-size turbines where the curvature is less in the length of a blade, this is not essential, because the chord departs so little from the arc. The bottom face 36 of the slot 35 is shown slightly oblique to the face 33. to provide a flare between such bottom face 36 and the back face 34 of the overlapping blade toward the discharge end of the slot. as this provides an expanding cross-section, which has an advantage if there is a relativelyv large drop in steam-pressure between one side of the diaphragm l() and the other; but this flare between the bottom face Btl and the surface 34 is not essential. and would ordinarily not be used if the drop in pressure between one side of the diaphragm l() and the other is small. If this flare provided, it. is to be noted that it is a flare in the passage-dimension transverse to the radial dimension of such steam passage, with such radial dimension maintained substantially constant by the parallelism of the faces 39 and 40. The parallel faces 39 and 40, however, do not extend all the way to the base ot' the finger 3l, but only extend to the throat 4l of the passage. On the receivr that particular nozzle passage.

mamar ing side of this throat 41, the adjacent walls of the flanges 37 and 88 converge from the base of the linger to such thoat, by reversecurve faces 43 and 44 which are substantially tangent at the throat end with the faces 39 and 4() and at the receiving end are substantiallyv tangent with the faces 23 and 22. This provides a convergent passage on the receiving side of the throat 4l, with the convergence in the radial dimension of such passage. This convergence forms the bulli of the convergence toward the throat 4l, though there is some convergence also by the surface of the hub 30 and the back face 34 of the overlapping blade.

By this construction, each steam passage past the diaphragm 10 is formed 'by the simple surfaces 22 and Q3 on the large parts lt) and 20 where machine work is dicult and costly, and by special surfaces which are formed wholly in the blades themselves, which are small and light and can be more conveniently handled for the forming of such special surfaces. Each steam passage starts between the hubs 30 of two adjacent blades, and between the surfaces 22 and 23, until it reaches the bases of the surfaces 43 and 44. There the passage converges rapidly to the throat 4l, and from the bases of such surfacesv43 and 44 the steam-passage surfaces are formed wholly in the two overlapping blades which co-operate to form After the throat 41 is passed, the steam passage continues between the faces 34 and 36, and 3i) and 40, until the discharge face is reached. from which face the steam is projected into the blades l5.

l claim as my invention:

l. Tn a turbine, the combination of a plurality of nozzle blades, and a support having faces between which said nozzle blades are mounted, said faces being parallel to each other and to the axis of the turbine, and fit-ting against the adjacent faces of the blades, two adjacent blades being arranged to overlap to form with said supporting members a stea fri-nozzle passage, said steamnoyzle passage being arranged to converge to a throat and to pass on beyond such throat divergently by surfaces which are formed wholly in the blades.

2. In a turbine, the con'ibination of a plurality of nozzle blades, and a support having faces between which said nozzle blades are mounted, said faces being parallel to cach other, and vfitting against the adjacent faces of the blades, two adjacent blades being arranged to overlap to form with said supporting members a steam-nozzle passage, said steam-nozzle passage being arranged to converge to a throat and to pass on beyond such throat divergently by surfaces which are formed wholly in the blades.

3. In a turbine, the combination of a plurality of nozzle blades, and a support having faces between which said nozzle blades are mounted, said faces being parallel to each other and to the axis of the turbine, and fitting against the adjacent faces of the blades, two adjacent blades being arranged to overlap to form with said supporting members a steam-nozzle passage, said steamnozzle passage being arranged to converge to a throat and to pass on beyond such throat by surfaces which are formed wholly in the blades. j j

4. In a turbine, the combination of a plurality of nozzle blades, and a support having faces between which said nozzle blades are mounted, said faces being parallel to each other, and fitting against the adjacent faces of the blades, two adjacent blades being arranged to overlap to form with said supporting members a steam-nozzle passage, said steam-nozzle passage being arranged to converge to a throat and to pass on beyond such throat by surfaces which are formed. wholly in the blades.

5. In a turbine, the combination of a plurality of nozzle blades, and a support having faces between which said nozzle blades are mounted, said faces being parallel to each other and to the axis of the turbine, and fitting against the adjacent faces of the blades, each of said blades having a tapering finger, with the tip of the finger overlapping the base of the finger of an adjacent blade, and the overlapping face of a blade being provided with a slot which co-operates with the overlapping face of the adjacent blade to form a steam-nozzle passage which converges to a throat formed wholly in said slot.

6. In a turbine, the combination of a plurality of nozzle blades, and a support having faces between which said nozzle blades' are mounted, said faces being parallel to each other, and fitting against the adjacent faces of the blades, each of said blades hav-y ing a tapering finger, with the tip of the` finger overlapping the base of the finger of an adjacent blade, and the overlapping face of a blade being provided with a slot which co-operates with the overlapping face of the adjacent blade to form a steam-nozzle passage which converges to a throat formed wholly in said slot.

7. In a turbine, the combination of a plurality of nozzle blades, and a support having faces between which said nozzle blades are mounted, said faces being parallel to each other and to the axis of the turbine, and fitting against the adjacent faces of the blades, each of said blades having a tapering finger, with the tip of the finger overlapping the base of the finger of an adjacent blade, and the overlapping face of a blade being provided with a slot which co-operates with the overlapping face of the adjacent blade to form a steam-nozzle passage which converges to a throat formed wholly in said slot, said steam-nozzle passage being substantially rectangular in cross-section throughout.

8. In a turbine, the combination of a plurality of nozzle blades, and a support having faces between which said nozzle blades are mounted, said faces being parallel to each other, and fitting against the adjacent faces of the blades, each of said blades having a tapering finger, with the tip of the finger loverlapping the base of the finger of an adjacent blade, and the overlapping face of a blade being provided with a slot which cop-operates with theI overlapping face of the adjacent blade to form a steam-nozzle passage which converges to a throat formed wholly in said slot, said steam-nozzle passage being substantially rectangular in cross-section throughout.

9. In a turbine, the combination of a plurality of nozzle blades, and a support having faces between which said nozzle blades are mounted, said faces being parallel to each otherand to the axis of the turbine, and fitting against the adjacent faces o-f the blades, each of said blades having a tapering finger, with the tip of the finger overlapping the base of the finger of an adjacent blade, and the overlapping face of a blade being provided with a slot which cooperates with the overlapping face of the adjacent blade to form a steam-nozzle passage which converges to a throat formed wholly in said slot, the discharge faces of said fingers beyond the parts where the fingers are overlapped by adjacent blades being substantially flush with each other.

l0. In a turbine, the combination of a plurality of nozzle blades, and a support having faces between which said nozzle blades are mounted, said faces being parallel to each other, and fitting against the adjacent faces of the blades, each of said blades having a tapering finger, with the tip of the finger overlapping the base of the finger of an adjacent blade, and the overlapping face of a blade being provided with a slot v which co-operates with the overlapping face of the adjacent blade to form a steam-nozzle passage which converges to a throat formed wholly in said slot, the discharge faces of said fingers beyond the parts where the fingers are overlapped by adjacent blades being substantially flush with each other.

11. In a turbine, the combination of a plurality of nozzle blades, and a support having faces between which said nozzle blades are mounted, saidl faces being parallel to each other and to the axis of the turbine, and fitting against the adjacent faces of the blades, each of said blades having a tapering finger, with the tip of the finger overlapping the base of the finger of an adjacent blade, and the overlapping face of a blade being provided rWith a slot Which cooperates with the overlapping face of the Vadjacent blade to form a steam-nozzle passage Which converges to a throatl formed wholly in sa-idslot, the discharge faces of said fingers beyond the parts Where the fingers are overlapped by adjacent. blades be- `ing substantially flush With each other and ing faces between Which said nozzle blades are mounted, said faces being parallel to each other, and fitting against the adjacent faces of the blades, each of said blades having a tapering finger, with the tip of the fingerL overlapping the base of the finger of an adjacent blade, and the overlapping face of a blade being provided With a slot which 3o-operates with the overlapping face of the adjacent blade to form a steam-nozzle passage which converges to a throat formed Wholly in said slot, the discharge faces of said fingers beyond the parts Where the fingers are overlapped by adjacent blades being substantially Hush with each other and substantially perpendicular to the axis of the machine.

ln Witness whereof, l have hereunto set my hand at Indianapolis, Indiana, this 19th day of March.l A. D. one thousand nine hundred and twenty three.

HENRY H. WAl'lD 

